Reentrant libraries

Abstract

PCT No. PCT/DE93/00256 Sec. 371 Date Jun. 27, 1995 Sec. 102(e) Date Jun. 27, 1995 PCT Filed Mar. 22, 1993 PCT Pub. No. WO94/22080 PCT Pub. Date Sep. 29, 1994A protective mutex switch is used in data processing installations for control of execution paths within processes. Library subroutines are protected by shell subroutines with the original name and thereby, establish the synchronization of processes using the libraries.

I claim: 
     
       1. A protective method for subroutines in a data processing system having at least one processor and a control for a plurality of execution paths within a process running upon execution of a program, comprising the steps of: providing an exclusive means for serializing subroutines for said number of execution paths;   providing a root part of said program code which is specific to a task of the program and which is not altered by the protective method and which uses library subroutines marked by original names as predetermined identifiers;   at least one of the library subroutines marked by said predetermined identifiers using an operation of a type that is incompatible with execution by a plurality of execution paths;   providing a library which contains said at least one incompatible library subroutine to be protected;   altering a name of said at least one subroutine to be protected from an original name to an altered name;   for each library subroutine to be protected, providing a shell subroutine which has the original name used by the root part;   using the exclusive means for serializing execution paths to provide an exclusive execution path of said at least one subroutine; and   using said shell subroutine of said original name to call up said at least one subroutine to be protected using said altered name to enact a function of said at least one subroutine to be protected.   
     
     
       2. A protective method as claimed in claim 1, further comprising the steps of: classifying the library subroutines to be protected according to operating means used which are incompatible with execution by a plurality of execution paths;   dividing the library subroutines into classes each having pairs of different operating means of this type; and   assigning to each class a dedicated exclusive means for use by the shell subroutines.   
     
     
       3. A method for protecting a plurality of execution paths running during execution of a program in a computer, comprising the steps of: providing a library of subroutines which are called by the plurality of execution paths, said library of subroutines including at least one subroutine which is incompatible with parallel execution by said plurality of execution paths;   providing an exclusive control means for serializing the plurality of execution paths;   renaming said at least one subroutine from an original name to a different name;   providing a shell subroutine having a same name as said original name of said at least one subroutine, said shell subroutine when called by said program performing the steps of: setting said exclusive control means to exclude subsequent calls,   running said at least one subroutine under said different name, and   resetting said exclusive control means to a non-exclusive setting after execution of said at least one subroutine so that said program executes said at least one subroutine of said different name exclusively by calling said shell subroutine of said original name.     
     
     
       4. A method as claimed in claim 3, further comprising the steps of: determining which subroutines of said library of subroutines are incompatible with parallel execution by said plurality of execution paths;   classifying said plurality of subroutines in said library of subroutines according to compatibility with parallel execution by said plurality of execution paths; and   assigning each class of subroutines to an exclusive control means so that subroutines of each class may be executed in parallel by said plurality of execution paths.   
     
     
       5. A method for protected execution of subroutines in parallel processing, comprising the steps of: providing a calling program code including calls to subroutines of a subroutine library;   determining which subroutines of said subroutine library are incompatible with parallel execution;   providing an exclusive control means for serializing the plurality of execution paths for said subroutines which are determined to be incompatible with parallel execution;   renaming said subroutines which are determined to be incompatible with parallel execution to altered subroutine names;   providing a shell subroutine for each of said subroutines which are determined to be incompatible with parallel execution, said shell subroutines being named a same name as an original name of a corresponding one of said subroutines which are determined to be incompatible with parallel execution, each of said shell subroutines performing the steps of: setting said exclusive control means for exclusive operation,   calling said corresponding one of said subroutines for execution by calling said altered subroutine names,   returning said exclusive control means for non-exclusive operation upon completion of said execution of said corresponding one of said subroutines; and     executing said calling program code for parallel processing so that said shell subroutines are executed when said original names of said subroutines which are determined to be incompatible with parallel execution are called, wherein said shell subroutines call corresponding ones of said original subroutines using said altered subroutine names.